1. Field of the Invention
The present application relates to new, substituted 2-acetamido-5-aryl-1,2,4-triazolones, to processes for preparing them, to their use alone or in combinations for the treatment and/or prevention of diseases and also to their use for the production of medicaments for the treatment and/or prevention of diseases, more particularly for the treatment and/or prevention of cardiovascular disorders.
2. Brief Description of the Prior Art
The liquid content of the human body is subject to various physiological control mechanisms the purpose whereof is to keep it constant (volume homeostasis). In the process, both the volume filling of the vascular system and also the osmolarity of the plasma are continuously recorded by appropriate sensors (baroreceptors and osmoreceptors). The information which these sensors supply to the relevant centres in the brain regulate drinking behaviour and control fluid excretion via the kidneys by means of humoral and neural signals. The peptide hormone vasopressin is of central importance in this [Schrier R. W., Abraham, W. T., New Engl. J. Med. 341, 577-585 (1999)].
Vasopressin is produced in specialized endocrine neurones in the Nucleus supraopticus and N. paraventricularis in the wall of the third ventricle (hypothalamus) and transported from there along its neural processes into the posterior lobes of the hypophysis (neurohypophysis). There the hormone is released into the bloodstream according to stimulus. A loss of volume, e.g. as a result of acute bleeding, heavy sweating, prolonged thirst or diarrhoea, is a stimulus for intensified outpouring of the hormone. Conversely, the secretion of vasopressin is inhibited by an increase in the intravascular volume, e.g. as result of increased fluid intake.
Vasopressin exerts its action mainly via binding to three receptors, which are classified as V1a, V1b and V2 receptors and belong to the family of G protein-coupled receptors. V1a receptors are mainly located on the cells of the vascular smooth musculature. Their activation gives rise to vasoconstriction, as a result of which the peripheral resistance and blood pressure rise. Apart from this, V1a receptors are also detectable in the liver. V1b receptors (also named V3 receptors) are detectable in the central nervous system. Together with corticotropin-releasing hormone (CRH), vasopressin regulates the basal and stress-induced secretion of adrenocorticotropic hormone (ACTH) via the V1b receptor. V2 receptors are located in the distal tubular epithelium and the epithelium of the collecting tubules in the kidney. Their activation renders these epithelia permeable to water. This phenomenon is due to the incorporation of aquaporins (special water channels) in the luminal membrane of the epithelial cells.
The importance of vasopressin for the reabsorption of water from the urine in the kidney becomes clear from the clinical picture of diabetes insipidus, which is caused by a deficiency of the hormone, e.g. owing to hypophysis damage. Patients who suffer from this clinical picture excrete up to 20 litres of urine per 24 hours if they are not given replacement hormone. This volume corresponds to about 10% of the primary urine. Because of its great importance for the reabsorption of water from the urine, vasopressin is also synonymously referred to as antidiuretic hormone (ADH). Logically, pharmacological inhibition of the action of vasopressin/ADH on the V2 receptor results in increased urine excretion. In contrast to the action of other diuretics (thiazides and loop diuretics), however, V2 receptor antagonists cause increased water excretion, without substantially increasing the excretion of electrolytes. This means that by means of V2 antagonist drugs, volume homeostasis can be restored, without in the process affecting electrolyte homeostasis. Hence drugs with V2 antagonist activity appear particularly suitable for the treatment of all disease conditions which are associated with an overloading of the body with water, without the electrolytes being effectively increased in parallel. A significant electrolyte abnormality is measurable in clinical chemistry as hyponatraemia (sodium concentration <135 mmol/L); it is the most important electrolyte abnormality in hospital patients, with an incidence of ca. 5% or 250 000 cases per year in the USA alone. If the plasma sodium concentration falls below 115 mmol/L, comatose states and death are imminent.
Depending on the underlying cause, a distinction is made between hypovolaemic, euvolaemic and hypervolaemic hyponatraemia. The forms of hypervolaemia with oedema formation are clinically significant. Typical examples of this are syndrome of inappropriate ADH/vasopressin secretion (SIAD) (e.g. after craniocerebral trauma or as paraneoplasia in carcinomas) and hypervolaemic hyponatraemia in liver cirrhosis, various renal diseases and cardiac insufficiency [De Luca L. et al., Am. J. Cardiol. 96 (suppl.), 19L-23L (2005)]. In particular, patients with cardiac insufficiency, in spite of their relative hyponatraemia and hypervolaemia, often display elevated vasopressin levels, which is seen as the consequence of generally disturbed neurohumoral regulation in cardiac insufficiency [Francis G. S. et al., Circulation 82, 1724-1729 (1990)].
The disturbed neurohormonal regulation essentially manifests itself in an elevation of the sympathetic tone and inappropriate activation of the renin-angiotensin-aldosterone system. While the inhibition of these components by beta receptor blockers on the one hand and by ACE inhibitors or angiotensin receptor blockers on the other is now an inherent part of the pharmacological treatment of cardiac insufficiency, the inappropriate elevation of vasopressin secretion in advanced cardiac insufficiency is at present still not adequately treatable. Apart from the retention of water mediated by V2 receptors and the unfavourable haemodynamic consequences associated therewith in terms of increased backload, the emptying of the left ventricle, the pressure in the pulmonary blood vessels and cardiac output are also adversely affected by V1a-mediated vasoconstriction. Furthermore, on the basis of experimental data in animals, a direct hypertrophy-promoting action on the heart muscle is also attributed to vasopressin. In contrast to the renal effect of volume expansion, which is mediated by activation of V2 receptors, the direct action on the heart muscle is triggered by activation of V1a receptors.
For these reasons, substances which inhibit the action of vasopressin on the V2 and/or on the V1a receptor appear suitable for the treatment of cardiac insufficiency. In particular, compounds with combined activity on both vasopressin receptors (V1a and V2) should both have desirable renal and also haemodynamic effects and thus offer an especially ideal profile for the treatment of patients with cardiac insufficiency.
The provision of such combined vasopressin antagonists also appears to make sense inasmuch as a volume diminution mediated solely via V2 receptor blockade can entail the stimulation of osmoreceptors and as a result a further compensatory increase in vasopressin release. As a result, in the absence of a component simultaneously blocking the V1a receptor, the harmful effects of the vasopressin, such as for example vasoconstriction and heart muscle hypertrophy, could be further intensified [Saghi P. et al., Europ. Heart J. 26, 538-543 (2005)].
WO 99/54315 discloses substituted triazolones with neuroprotective activity, and WO 2006/117657 describes triazolone derivatives as anti-inflammatory agents. Furthermore, EP 503 548-A1 and EP 587 134-A2 claim cyclic urea derivatives and their use for the treatment of thromboses. Substituted triazole thiones as ion channel modulators are disclosed in WO 2005/097112. WO 2007/134862 describes substituted imidazol-2-ones and 1,2,4-triazolones as vasopressin receptor antagonists for the treatment of cardiovascular disorders.